1. Field of the Invention
The present invention generally relates to a control key unit. More specifically, the present invention relates to a control key unit for a television receiver.
2. Background Information
A conventional liquid crystal television receiver has a cabinet and a control key unit. The cabinet has a front cabinet and a rear cabinet. The front cabinet is rectangular when viewed from the front. The rear cabinet is coupled to the front cabinet. The control key unit includes a plurality of key tops. The key tops stick out from openings of the front cabinet. The openings are formed at a plurality of locations in a side panel on one side of the front cabinet, and are aligned vertically. The key tops are pressed by the user to set various modes. The key tops include a main power button, channel changing buttons, volume adjusting buttons, an external power switchover button, setup buttons, and other such necessary control buttons.
The control key unit is attached to the side panel of the front cabinet. The control key unit further includes a vertically oriented rectangular wiring board and a vertically oriented frame. A plurality of key switches is installed on the wiring board in a vertical alignment.
With the control key unit, the wiring board is attached to the frame. The key tops are integrally molded with the frame from resin. The key switches are mounted on the wiring board, and are disposed on the back of the key tops, respectively.
With the control key unit, the wiring board is temporarily positioned in a lengthwise direction and a width direction of the wiring board by the action of positioning protrusions that stick out from the frame. Then, the wiring board is fastened with attachment screws to the frame at a plurality of places (three places, for example). When this constitution is employed, the wiring board is positioned not only in the lengthwise direction and the width direction, but also in a thickness direction of the wiring board, by the positioning protrusions and the attachment screws. Because of the need to employ this attachment structure, the necessary number of screw holes and positioning holes are formed passing through the wiring board at the required places.
With the control key unit, the wiring board is attached to the frame. The control key unit is further attached to the side panel of the front cabinet by using attachment screws. The attachment screws fasten attachment tabs provided at both ends of the frame in the lengthwise direction of the frame to bosses provided to the front cabinet.
Meanwhile, there has been proposed another structure for attaching a wiring board to a housing of an electrical device. With the structure, a switch (e.g., key switch) is mounted on the wiring board. The switch is pressed by a control button. Furthermore, the two ends of the wiring board are inserted into a pair of U-shaped fixing tabs. Moreover, a plurality of hook-shaped support tabs is provided to the housing, and is engaged with the wiring board, thereby preventing the wiring board from coming loose from the fixing tabs (see Japanese Laid-Open Patent Application Publication No. H7-141961, for example).
Also, with further another structure, a wiring board on which a tactile switch is mounted is attached with a single screw to a button chassis having an integral push button. The wiring board is positioned by fitting a single stabilizing pin provided to the button chassis into an insertion hole in the wiring board (see Japanese Laid-Open Patent Application Publication No. H3-674425, for example).
However, with the conventional structure in which the wiring board is screwed down, not only is the components cost higher because of the need for using attachment screws, but the assembly process is more complicated because the time-consuming screw-fastening work has to be carried out. Thus, it is difficult to improve productivity.
Also, with the conventional structure in which the two ends of the wiring board are inserted into the fixing tabs, and the wiring board is held in place by the support tabs, when warping, bending, or other deformation occurs in the wiring board, there is no action to correct the deformation. Accordingly, the warping, bending, or other deformation remains even after attaching the wiring board. Furthermore, if this happens, the operation of the switches mounted on the wiring board by pressing the push buttons will be unstable, or the tactile feedback to the user will be inconsistent when the push buttons are pressed. As a result, it is difficult to increase the operational quality of the electrical device.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved control key unit. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.